What do you do for a patient with Parkinson's Disease and orthostatic hypotension who has failed midodrine, fludrocortisone, droxidopa, pyridostigmine, and atomoxetine?  

I would not recommend using amantadine in this situation as it is known to worsen orthostatic hypotension (Perez-Lloret et al., PMID 22336566). This is a tricky situation, and if the patient has failed all of these medications, I would consider an alternate diagnosis, specifically MSA, especially if...

I would approach this in several ways. Conservative strategies to increase blood pressure, including compression stockings (thigh high), abdominal binder, salt supplementation, good hydration, etc Stop all meds that could be reducing blood pressure (don’t forget meds for prostate problems)...